02.19.2016
Written By: Becca Mackenzie
Today we did a few different experiments to introduce the students to the very cool properties of light. We had 5 stations that emphasized a different property of light that each group spent ~10 minutes at. Normally we start the day with a small presentation about the lead mentor’s background and research, but today, since we had so much to do, we skipped that and jumped right into the experiments.
The 5 stations were
- White light = all the colors added together. Here we had red, green, and blue flashlights that when added together give you white light. We also had color transparencies and diffraction gratings.
- Light = energy. Here we had a solar cell hooked up to a small radio and a second one hooked up to a multimeter. The students had a variety of light sources (regular white light, green, red, blue, transparencies, UV, polarizers) that they could test out on the solar cell to conclude what the best light source is for the solar cell.
- Light has an orientation. Here we had a few polarizers that the students could play with- seeing that the light was completely blocked only at certain orientations. Also, computer screens are polarized, so they were also introduced to the idea that some light sources are already polarized.
- Plants use light as an energy source. Here we had spinach, cauliflower, tomatoes, carrots, and cucumbers. The students blended a vegetable with IPA and then shined regular light or UV light on the liquid. Chlorophyll glows red under UV light. Apart from being really awesome, this experiment led the students to think about the relationship between plants and sunlight.
- Absorbance. Here we had invisible ink pens that glowed under UV light. We also had sunscreen to block the UV light and thus stop the fluorescence of the ink. This demonstrated that different substances absorb different wavelengths. We also talked about the danger of UV light and why sunblock is necessary. Furthermore, for the students that had glasses on, you could demonstrate that their glasses have a coating that blocks UV light to protect their eyes.
Overall, the day went smoothly, and I think the students got a lot out of the experiments. I think it was helpful that the previous lessons were on sound waves, since that gave them background on wave properties. I’m looking forward to next week when we take these lessons and apply them to an experiment on light and plant growth.